Carburetor



w. c. CARTER Feb. 7, 1933.

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Feb; 7, 1933. w c CARTER 1,896,390

CARBURETOR Filed June 11, 1930 3Sheets-Sheet 2 I\\\\\\\\\\\\\\\\\\\\\\%$W'fi iii lA/VENTOE:

3 Sheets-Sheet 3 Feb. 7, 1933. w. c. CARTER CARBURETOR Filed June 11,1930 rro e/vcKs.

Patented Feb. 7, 1933 UNITED STATES WILLIIEAM C. CARTER, OF FLINT,MICHIGAN CARBURETOB Application filed June 11, 1930. Serial No. 460,371.

This invention relates to carburetors of the kind that are used oninternal combustion engines. I

One object of the invention is to provide a carburetor of improveddesignthat has two separate and distinct fuel ranges, i. e., a powerrange in which the proportion or ratio of fuel to air is relatively highand great enough to produce adequate power for a heavy load, and aneconomy range in which the ratio or proportion of fuel to air isconsiderably lowor, but is sufficient to take care of the requirementsat idle speeds or when the engine is operating under a normal load ormaximum load. 1

Another object is to provide a multi-fuel range carburetor of the kindabove described, which is of such design that there is no fiat spot orperceptible variation in the ratio of fuel to a r when the change fromone range to the other occurs.

Another object is to provide a carburetor that embodies the desirablefeatures and characteristics of a plain tubecarburetor and a mechanicalcarburetor, and which is of such design that when the engine isoperating under a heavy load with a wide open throttle, the carburetorwill act as a plain tube carhuretor whose fuel ratio is high enough toproduce greatpower, and when the engine is idling or is operating undera normal load, with the throttle valve in an intermediate position ornearly closed. the carburetor will act as a mechanical carburetor whosefuel ratio is considerably lower than the fuel ratio which prevails whenthe carhuretorjs acting as a plain tube carburetor.

Another object is to provide a carburetor which is of such design thatwhen the throttle valve is in its wide open position, the supply of'fuelto the main passageway is not dependent entirely upon the suction thatexists in said mam passageway at such times, there'- by making itPOSSlblQ to construct the carhuretor so that sufficient fuel will besuppl ed to the main passageway to take care of a heavy load thatis'imposed on the engine when the throttle valve is in its wide openposition, even though the airis flowing through the main passageway atsuch a low velocity as to fuel to air at all speeds and varying loads,and

which is of such design that the engine can be easily started in coldweather. Other objects and desirable features of my invention will hehereinafter pointed out.

Figure 1 of the drawings is a side elevatfonal view of a carburetorembodying my present invention, partly broken away to illustrate theconstruction of the extensible link that forms part of the mechanism fortransmitting movement from the throttle valve to the air admissionvalve.

Figure 2 is a side elevational view of said carburetor, partly brokenaway to illustrate the construction of the vacuum pot and the dash potthat are combined with the air ad- 1111851011 valve.

Figure 3 is a side elevational view of the opposite side of thecarburetor, illustrating the choking mechanism.

Figure 4 is a top plan view of the carburetor.

Figure 5 is .a vertical longitudinal sectional view of the carburetor.

Figure 6 is a fragmentary vertical transverse sectional view, taken onthe line 66 of Figure 5, looking in the direction indicated by thearrows.

Figure 7 is a viewsimilar to Figure 6, illustrating another means thatmay be used to interruptthe action of the fuel siphon when the engine isstopped; and

Figure 8 is a facsimile of an indicator card produced on a flow bench onwhich my improved carburetor was tested.

In the accompanying drawings I have illustrated my invention embodied ina downdraft carbureto'r, but I wish itto be understoodthat the inventionis applicable. to an updraft carburetor. The carburetor is provided witha main passageway equipped with a throttle valve B attached to a rockshaft 1 that has an arm 2 to which an operat ing rod 3 and return spring4 are attached, as shownin Figure 3, said return spring being of suchtension that it tendsto hold the throttle valve in its closed position.The

main passageway A is also provided with an air admisslon valve C, which,in the form of Connecting mechanism for throttle valve and air admtsszonvalve The connection between the valves B and C, or the mechanism thatis used for trans mittmg movement from the throttle valve to the airadmission valve, consists of a fixed or rigid arm 6 on one end of thethrottle valve shaft 1 (see Figures 1 and 2), a rigid link 7 and anextensible link D pivotally connected by a pivot 6 to the free end ofthe arm 6 and leading upwardly from same, two rock arms 8 and 9 looselymounted on one end of the shaft 5- of the air admission valve andpivotally connected to the upper ends of the links 7 and D,respectively, by pivots 10 and 10", a laterally-projecting pin or device11 on the free end of the rock arm 9 arranged so as to engage orbearagainst a stop screw 12 mounted in an. extension 8' on the rock arm8 that projects beyond the pivotal connection 10 between the rigid link7 and the rock arm 8, a rigid or fixed lever E on the air admissionvalve shaft 5 provided with a laterally projecting lip or extension 13that laps over and bears against the underside of the rock arm 9, and avacuum pot designed as an entirety by the reference character Fcharacter ingly mounted in sai whose cylinder'is pivotally connected bya pivot 13 to the outer end of the lever E. The said mechanism alsocomprises a dash pot, designated as an entirety by the reference G, thati's'used to retard or check the opening movement of the air admissionvalve. 1 m I The extensible link D previously referred to is composed oftwo telescoped or relatively movable sections 14 and14? combined with acontractile sprin 15 in such a way that said spring tends to old thelink D in its contracted condition; The vacuum pot F is composed of aninverted cylinder 16 whose upper. end is provided with a lug forreceiving the pivot 13, and a is'ton 17 is reciprocatd cylinder. Saidpiston is provided with a rigid piston rod 18 that is rockably mountedon the body of. the carfburetor in such away that the vacuum pot F as anentirety is capable of rocking'about an axis 19. A suction duct orpassageway 20 1S formed in the piston 17 and piston rod 18 for exertinga downward pull on the cylinder 16,

the upper end of the said suction passageway 20 terminating in the topface of the piston 17, and the lower end of said duct, designated by thereference character 20 in Figure 5, terminating in the main passageway Aat a point between the throttle valve B and the intake of the engine onwhich the carburetor is used. The dash pot G, previously referred to,can be constructed and arranged in various ways without departing fromthe spirit of my invention, but it is herein illustrated as beingcomposed of a cylinder 21, rigidly attached to the cylinder 16 of thevacuum pot and a piston 22-reciprocatingly mounted in the cylinder 21and provided with a ri id piston rod'23 whose lower end is pivotal yconnected at 24 to a rigid arm 25 on the lower end of the piston rod 18of the vacuum (through the duct 20) in a direction tending to move saidcylinder downwardly and cause the lateral extension 13 on the lever E toremain in engagement with and follow the rock arm 9 which swingsupwardly with the rock arm 8 that is joined by the rigid link 7 to thearm 6 on the throttle valve shaft.

When a certain approximatc'suction exists in the intake of the engine,the downward pull which the vacuum pot exerts on the outer end of thelever E holds the spring 15 stretched and causes thelaterally-projecting pin 11 on the arm 9 to remain in engagement withthe stop screw 12 in the extension at the end of the rock arm 8.Hereafter I will explain how the mechanism just described governs therelative position of the throttle valve and air admission valve andpermits or causes said valves to assume different positions relativelyto each other at different periods in the cycle of operations of thecarburetor.

Fuel supply means Liquid fuel is introduced into the main passageway Aat a point intermediate the throttle valve B and air admission valve Cby a fuel nozzle H, or other suitable type of fuel supplying device,arranged so that fuel will be discharged from same' in the direction oftravel of the air that is flowing through the main passageway A. In adowndraft carburetor, as herein illustrated, the nozzle H will dischargedownwardly, as shown in Figures 5 and 6. The nozzle H is carried by atubular member 26 disposed discharge end or outlet of said nozzle H islocated at a point below the fuel level a: of

the float chamber I of the carburetor. Preferably, a suction amplifierherein illustrated as a venturi A is arranged inside of the mainpassageway A at such a point that the discharge end of the nozzle Hterminates in the contracted portion of said venturi Due to the factthat the suction in the main passageway Aiis not relied upon entirely tosupply fuel to said passageway, it is possible to make the venturi Amuch larger than is the usual practice, thus increasing the volume ofthe air flowing through the passageway A when the throttle valve is wideopen.

Fuel escapes from the float chamber I of the carburetor through anoutlet 27, and then passes through a fuel orifice 28 into afuelpassageway 29 formed in the side wall of the main passageway A andlocated at a point considerably below the discharge opening of thenozzle H, said fuel passageway 29 having a branch .29 which leadsupwardly, as shown in Figure 5, and communicates at its upper end withthe interior of the tubular member 26 that carries the fuel nozzle H. Byreferring to Figure 5, it will be noted that the upper end of the fuelpassageway 29 terminates at a point above or-higher than the fuel levelof the float chamber, and it will also be noted that the dischargeopening of the nozzle H is located at a point below the fuel level :0 ofthe float chamber. Under certain conditions, hereinafter described, thefuel orifice 28 is unobstructed, thus permitting a relatively greatquantity of fuel to pass through said orifice and enter the passageway29' that leads to the fuel nozzle, and under different conditions theflow of fuel through the orifice 28 is restricted by a fuel valve J,preferably a needle valve,

combined with a spring 30 that exerts pressure on same in a directiontending to hold the valve J open, or in such a positlon as to notrestrict the flow of fuel through theorifice 28. The fuel valve J ismoved in the opposite direction, i. e., towards its seat, by a rockedlever K pivotally connected with the upper end portion of said valve andprovided with a track K (see Figures 1 and 2) that co-acts with a cam Kon the rock arm 8 previously referred to, which is attached by the rigidlink 7 with the arm 6 on the throttle valve shaft. Movement of thethrottle valve B towards its closed position causes the cam K to rockthe lever K downwardly, with the result that the fuel valve J will movetowards its closed position, and thus cut down or restrict the flow offuel through the fuel orifice 28. hen the throttle valve moves towardsits open position, the cam K travels over the track K in a direction topermit the lever K to rock upwardly, due to the upward pressure whichthe spring-pressed fuel valve J is constantly exerting on the lever K. IDuring the economy range the supply of fuel to the main passageway A isvarled automatically, according to the position of the throttle valve bya change in the position of the fuel valve J whose position at suchtimes is gov-v erned by a mechanism controlled or operated by thethrottle valve, and during the power range an entirely different means,hereinafter described, is used to govern the admission of the fuel tothe main passageway A.

The mechanism that transmits movement from the throttle valve to the airadmission valve is so designed that when the carburetor is actlng as amechanical carburetor, the air admission valve C will be held insubstantially parallel relationship with the throttle valve B, so as toproduce a high suction zone between said valves that is exerted on thefuel orifice 28, which, at such times is restricted by the fuel valve J.The cam is and the lever K that are combined with the throttle valve andfuel valve form a very reliable means of simple design for varying theratio of fuel to air supplied to the main passageway A during theeconomy range. The suction that exists in the intake of the engine whenthe throttle valve is in a closed or intermediate position is alsoutilized to vary the supply of fuel to the nozzle H durmg the economyrange. If the throttle valve B is in a closed or partly closed position,the

high suction in the intake that is exerted on the suction passageway 20draws the cylinder of the vacuum pot downwardly, and thus causes thelaterally-projecting stop 11 on the long arm 9 to be held in engagementwith the stop screw 12 in the extension on the e d of the short arm 8,the spring 15 of the xtensible link D being held stretched or undertension at such times. If a heavy load is imposed on the engine, thesuction in the intake diminishes, and immediately the cylinder of thevacuum pot will move upwardly under the influence of the spring 15 ofthe extensible link D which contracts and draws the long arm 9downwardly, thereby causing the air admission valve C to moveindependently of and relatively to the throttle valve D into such aposition as to diminish or cut down the supply of air to the mainpassageway A. The downward movement of the arm- 9 is transmitted to theair admission valve by the lever E whose laterally-projecting lug 13engages the underside of the arm 9. As soon as the air admission valve Cmoves in this manner, i. e., towards its takes care of the extra loadimposed on the passagewayengine, and as soon as said extra load ceases,

' the high suction that is re-established in the intake below thethrottle valve again draws the cylinder of the-vacuum pot E downwardly,t us causing the air admission valve C to move in the oppositedirection, i. e., towards its open position, with the result that thesupply of air to the main passageway A will be increased. From theforegoingv it will be understood that during the economy range the linkD that forms part of the mechanism that transmits movement from thethrottle valve to the air admission valve is extended, thereby causingthe air admission valve to remain in parallel relationship with thethrottle valve, and when a load comes on the engine, said link Dcontracts and causes the air admission valve to move relatively to thethrottle valve into such a position as to automatically increase theratio of fuel to air, and thus supply sufficient fuel to take care ofthe extra load. While the ratio of fuel to air will, of course, varywith different engines, I have found that the carburetor is entirelysatisfactory if it is designed in such a way that under a normal loadwith a wide open throttle the fuel and air will be supplied in a ratioof about 81; lbs. of fuel per 100 lbs. of air, and under a normal loadwith the throttle valve in an intermediate position, the fuel and airwill be supplied in a ratio of about 7 lbs. of fuel per 100 lbs..of air.

When the carburetor is operating as a plain tube carburetor with thethrottle valve 13 and air admission valve C both wide open, the fuelvalve J is inactive and is held in its wide open position by the springwith which it is combined. Due to the fact that the venturi A onlyslightly restricts the flow of air through the passageway A when thethrottle valve is wide open, there is not suflicient suction exerted onthe fuel nozzle II when the engine is subjected to a heavy load with awide open throttle. to cause fuel to be drawn into the passageway A fromthe fuel nozzle. Accordingly, I have designed the carburetor so thatfuel will be supplied to the nozzle H at such times, either by asiphoning action or by gravity. In the carburetor herein shown asiphon-is used to deliver fuel from the float chamber I to the nozzle Hwhen the air entering through the main passageway A is traveling at thelowest velocity, and it is for this reason that I arrange thetlischargeend of the fuel nozzle H at a point below the fuel fuel of the floatchamber.

level a: of the float chamber and arrange the upper end of the fuelpassageway 293 so that it extends to a point above the level of the Thefuel orifice 28 is calibrated so that said orifice will supply thecorrect quantity offuel to produce the proper ratio of fuel to air undera normal load with awide'open throttle, i. e., at the intermediatevelocity of airflow-ingjthrough the main passageway A After the flow offuel upwardly through the fuel passageway 29 has been established, fuelwill continue toflow upwardly through said passageway, even though thesuction in the main passageway A diminishes co nsiderably,due to-anextra heavy load imposed on the engine when the throttle valve is wideopen. Consequent- 1y, when the velocity of the air flowing through thepassageway A is at minimum, sufficient fuel is supplied to saidpassageway by the action of the siphon, previously mentioned, to producea rich mixture that will successfully take care of the extra load on theengine. In view of the fact that the fuel ori fice 28 is calibrated soas to supply the proper quantity of fuel under a normal load with a wideopen throttle, said orifice 28 would supply too much fuel when thevelocity of the air flowing through the passageway A is at maximum, i.e., when the engine is operating under a light load with a wide'openthrottle. Accordingly, I provide the fuel valve J with an air vent 31,shown in broken lines in Figure 5, whose upper end communicates with theatmosphere at apoint outside of the main" passageway A. This air vent 31is subject to the same suction that the fuel outlet 27 of the floatchamber is subject to, but the size of the outlet 27 is considerablygreater than the size of the air vent 31. Accordingly, air

will not start to break in through the air vent 31 until the suctionexerted on the port 27 is equal to the weight of the fuel standing inthe air vent 31. By increasing the size of the outlet port 27, the timeat which air starts to break in through the vent 31 will be delayed.This will be clear from the chart shown in Figure 8, which illustratesthat when five hundred pounds of airper hour is drawn through the mainpassage, sufficient suction is exerted on the outlet 27 to equal theweight.

of fuel standing in the air vent 31, and at this time air begins to flowthrough the port 28 controlled by a needle valve, the ratio of fuel toair'continuing to drop until the maximum is reached. \Vhen air istraveling through the passageway A at the highest velocity, air entersthe fuel passageway 29 through the air vent 31 in the fuel valve, andthus diminishes the suction in said fuel passageway 29 sufficiently toprevent an excessive quantity of fuel being supplied by the nozzle I-I.

Unless some means were provided for breaking the siphon that causes fuelto be delivered to the main passageway A when the engine is operatingunder a heavy load with a wide open throttle, fuel would continue toescape from the nozzle H after the engine had been stopped, thus causingconsiderable waste of fuel and also causing the engine to becomeflooded. In order to pre-- valve 32 arranged to close a vent 26 may beused for this purpose consists of a leading from ,the interior of thetubular member 26 that carries the fuel nozzle H, and combined with asolenoid or similar electrically-operated device 33 that is connectedwith the ignition system of the engine. As shown in Figure 6, the valve32 is mounted on a member 34 constructed of magnetic material andarranged below the coil of the solenoid. As soon as the ignition circuitof the engine is closed, the solenoid moves the member 34 upwardly intoa position to close the air vent 26*. So long as the engine continues inoperation, the valve 32 will remain seated, but as soon as the engine isstopped by opening the ignition circuit, the member 34 drops downwardly,due to gravity, with the result that the interior of the tubular member26 will be vented, thus causing air to be admitted to the fuel assageway29 so as to break the siphon. Xnother means that may be used for thispurpose consists of a disk valve 35 that controls an air vent 26 leadingfrom the interior of the tubular member 26 that carries the fuel nozzleH, as shown in Figure 7. As soon asthe engine is started the suctionthat is created in the main passageway A of the carburetor causes thevalve 35 to move upwardly into engagement with its seat 36 and remainseated so long as the engine continues in operation. As soon as theengine stops the suction in the main passageway A will cease and thevalve 35, due to its weight, will drop downwardly into position to openthe air vent 26 and cause air to be supplied to the siphon to interruptthe action of same.

Choking mechanism 7 The carburetor is equipped with a choking mechanismfor facilitating starting of the engine. Said mechanism is soconstructed that when it is actuated by the operator in charge of theengine, the air admission valve C will be moved into its closed positionand the fuel valve J will be raised slight- 1y from its seat. The leverK. previously referred to, is pivotally connected at 40 to the upper endportion of the fue l valve J, and said lever is mounted in sucl a waythat it can be adiusted to vary th initial setting of the fuel valve andalso to raise said valve slightly from its seat during the operation ofchoking the engine. In the carburetor herein shown the lever K isprovided at one end with a laterally-projecting pin 41 (see Figure 4).that projects into an eccen'trically-disposed hole in a horizontal shaft42 that isrockably mounted in a bearing on the top wall of the floatchamber I. The choking mechanism comprises a manually-operable.-=eginental rack 43 (see Figure '3) mounted on one end of the shaft 42and arranged in mesh with a segmental rack 44 011 a rock arm 45 that isused to move the air admission valve C towards its closed position. When43 in the direction indicated by the arrow in Figure 3, such movement ofthe operating rod 46 causes the arm 45 to rock clockwise and co-operatewith arigid arm 47 on. the air admission valve shaft 5 to move the valve0 into its closed position, so as to choke or cut down the supply of airto the main passageway A while the engine is being cranked to start thesame. As the segmental rack 43 is connected with the shaft 42 in whichthe pivot 41 of the fuel valve control lever K iseccentrically mounted,the movement of the operating rod 46 in a direction to choke the enginecauses the shaft 42 to rock in a direction to bodily raise the lever Kand raise the fuel valve J slightly off its seat, thereby insuring asuflicient supply of fuel to start the engine, even in excessively coldweather, when the lubricating oil is stiff or congealed. I

In order that the fuel valve J may be initially adjusted or set closerto or farther away from its seatwhen the air'admission valve is in itsfully closed position, means is provided for adjustably connecting thesegmental rack 43 to the rock shaft 42 that serves as a shiftablebearing for the lever K. In the form of my invention herein illustratedthe means thatis used for this purpose consists of "a rigid arm 48 onthe shaft 42 (see Figure 3) provided with a pin 49 that is adapted to beinserted in any one of a row of arc-shaped holes 50 in the segmentalrack 43. The rack 43 is loosely mounted on the shaft 42, but when thepin 49 isinserted in one of the holes 50, the rack 43 will be rigidlyconnected with the shaft 42. By changing the relationship between thesegmental rack 43 and the rigid arm 48, the location of the supportingpivot 41 of the lever K will be changed, thereby enabling the degree ofthe opening movement of the fuel valve J to be changed to adapt thecarburetor to the particular engine on which it is used. The carburetoris so designed that in the operation of starting the engine the airadmission valve C will automatically open a slight degree and admit airto the passageway A as soon as the engine starts firing. Accordingly, Iinterpose a spring 51, or some other yielding 'or resilient buifer,between the arm 47 on the air admission valve shaft 5 and the arm 45 onthe segmental rack 44, so as to permit the air admission valve C to openslightly, even though the operator fails fir arm 47 on the shaft 5, butwhen the arm 47 rocks slightly in the reverse direction, due to the airadmission valve C opening automaticallywhen the engine starts firing,the spring 51 will yield, and thus not interfere with the movement ofthe arm 47.

Operation Assuming that the engine is in operation 'J which is held inits nearly closed position bv the lever K which co-operates with the cam31. At such times the suction in the intake of the engine that isexertedon the suction passageway 20 causes: the vacuum pot F to exert adownward pull on the free end of the lever E, with the result that thespring 15 of the'extensible link'D will be maintained under tension orin a stretched condition, and the laterally-projectingpin 11 on the longarm 9 will be held in engagement with the stop screw 12 on the short arm8. Movement of the throttle valve towards its open position causes theair. admission valve C to move towards its open position, and alsocauses the cam 31 to travel over the trackv K in a direction to permitthe fuel valve J to move away from its seat, and thus increase thesupply of fuel to the fuel passageway 29. An idle engine speeds, or whenthe engine is operating under a normal load with the throttle valve inan intermediate position, the throttle valve and the air admission valvewill move in unison and will be maintained in approximately parallelrelationship, and the fuel valve J will be moved towards or away -fromits-seat, depending upon the direction of movement and degree ofmovement of the throttle valve. During this range of operation of thecarburetor, which, for convenience, I have referred to as the economyrange, the quantity of fuel supplied to the fuel passageway 29 will besuch asto produce the correct or approximately correct ratio of fuel toair, which, as previously stated, is about 7 lbs. of fuel per 100 lbs.of air. The previously mentioned ratio of fuel ,to air will stayconstant or substantially so when the engine is operating under a normalload with the throttle valve in an intermediate position. VVhen the loadon the engine increases above normal the suction in the intake of theengine will diminish and the spring 15 of the extensible link D willimmediately contract and cause the long arm 9 to exert pressure however,remains in its former position,

due to the fact that the cam 31 which co-aets with the lever K thatcontrols the position of the fuel valve, is carried b the short rock arm8 which remains in its ormer position, 'due to the fact that said arm 8is joined by the rigid link 7 to the arm 6 on the throttle valve shaft.The fuel supply, however, is instantly increased because movement of theair admission valve towards its closed position creates a higher suctionin the main passageway A, and this higher suction draws more fuel out ofthe fuel orifice 28, with the result that the fuel range is changedautomatically from the economy range to the power range, wherein thefuel is supplied at an increased ratio, for example, per 100 lbs. ofair. As soon as the extra load on the engine ceases, the suction in theintake increases sufiiciently to draw the cylinder of the vacuum pot Fdownwardly, thereby restoring the air admission valve C to its formerposition and causing the quantity of fuel supplied to the fuelpassageway 29 to be-diminished or restored to the ratio that prevailsduring the economy range. Under the conditions just described thecarburetor may be properly said to be operating as a mechanicalcarburetor, because the air sup ply is varied by thevalve C and the fuelsupply is varied by changing the position of a fuel valve J that movestowards and away from its'seat as the position of the throttle valve isvaried.

Air gets under way faster than liquid fuel, and accordingly, if thethrottle valve of a, carburetor is positively connected with an airvalve that controls the suppl of air to the main passageway of the caruretor, a sudden movement of the throttle valve-towards its openposition so as to accelerate the engine is apt to result in too much airbeing supplied to the main passageway, o r,

in other words, supplied at a rate far in excess of the ratio thatshould be maintained between the fuel supply and air supply. In myimproved carburetor the dash pot G, previously referred to, prevents theair admission valve-C from opening at the same rate of speed as thevthrottle valve B when said throttle valve is kicked open to acceleratethe engine. If the throttle valve is opened suddenly, the air admissionvalve C will lag or travel towards its open position at a slower speedthan the speed of movement of the throttle valve. thus holding back theair and causing it to be admitted to the passageway A in approximatelycorrect ratio to the fuel.

When the throttle valve is moved into its wide open position, the airadmission valve C will also move into. its wide open position,

so as to not retard the flow of air through the 8 lbs. of fuel,

While it is true that the fuel valve J is inac-' tive or in its wideopen position at such times, i. e., when the throttle valve and airadmission valve are wide open, nevertheless, .the fuel is supplied tothe passageway A in varying quantities, but in such a ratlo of fuel toair as to produce a mixture that is correct for the particular load orvarying loads to which the engine is subjected under a wide openthrottle. At intermediate velocity of the air flowing through thepassageway A, when the throttle valve and air admission valve are wideopen, the suction that is exerted on the nozzle H causes the correctquantity of fuel to be drawn through the fuel orifice 28 to produce aratio of about 8 lbs. of fuel per 100 lbs. of air. If a heavy load isimposed on the engine the fuel ratio is increased automatically to, say,9 or 10 lbs. per 100 lbs. of air, as indicated by the indicator card inFigure 8. This highly desirable result is attained by constructing thecarburetor in such a way as to produce a siphon which supplies fuel tothe main passageway A under a heavy load with a wide open throttle, andone of the out standing advantages ofsuch a design is that it permitsthe main passageway A to be,

equipped with a venturi A which is so large or of such great diameterthat it does not materially restrict the flow of air through thepassageway A when the throttle valve of the carburetor is wide open.When the air is traveling through the passageway A at maximum velocity,sufiicient air is admitted to the fuel passageway 29 by the air vent 31in the fuel valve J to diminish the fuel sup-plied to the nozzle H andprevent the carburetor from being wasteful. Subsequently, whenthethrottle valve is moved towards its closed position, the air admissionvalve C comes into service so as to regulate the supply of air to thepassageway A, and the fuel valve J comes into service to regulate thesupply of fuel to was operating under a heavy load with a wide openthrottle.

In starting the engine the operator in charge of same pulls theoperating rod 46 in the direction indicated by the arrow in Figure 3, so-as to move the air admission valveC into its closed position. The speedat which the pistons of the engine travel when it is being cranked,either by hand or by an electrical starter, is not sufiicient to createa suction in the intake below the throttle valve that is of sulficientintensity to pull the cylinder of the vacuum pot downwardly. Hence,there is no tendency for the air admission valve C to open, after-it hasbeen closed by the choking mechanism, and before the engine startsfiring. As soon as the engine starts firing, however, the high suctionthat exists in the intake is exerted on the cylinder of the vacuum pot Fin a direction to slightly open the air ad-= mission valve C, thuscausing sufficient air to be supplied to the passageway A to prevent theengine from stalling or dying, even though the operator fails to restorethe operating rod 46 to its former position. This reverse movement oropening movement of the air admission valve C is made possible byinterposing a spring or other suitable buffer 51 between the rigid arm47 on theshaft 5 of the valve C, and the rock arm 45 of the chokingmechanism that co-acts with the arm 47 to move the valve C intoits'closed position. In addition to closing the valve C "so as to chokethe engine, the movement of the segmental rack 43 causes the fuel valveJ to be raised slightly from the seat, with 'the result that suflicientfuel will be supplied to the fuel passageway 29 to insure the enginestarting, even though the engine is cold and the lubricating oil of sameis congealed.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A carburetor provided with a main passageway through which airtravels to the intake of an engine, a throttle valve and an airadmission valve for said passageway, a suction amplifier arranged insaid main passageway between said valves, means for causing the positionof said air admission valve to change when the position of the throttlevalve is changed, means for closing said air no i admission valvewithout changing the position of said throttle valve, a fuel orifice forsupplying fuel to said main passageway a fuel valve for restricting saidfuel orifice under certain conditions, and an operating mechanism forchanging the position of said fuel valve, constructed so that said fuelvalve will act as a variable restriction for said fuel orifice in theintermediate positions of the throttle valve and will be maintained inan inactive or wide open position when the throttle valve and airadmission valve are wide open.

2. A carburetor of the kind described in claim 1, provided with meansseparate and 'distinct from the suction existing in the mainpassageway,for delivering fuel to said passageway when the engine is operatingunder a heavy load with a wide open throttle.

3. A carburetor provided with a throttle valve, an air admission valve,a mechanical connection between said valves, a variable fuel supplyingmeans controlled by the throttle valve, and a means controlled by thesuction in the intake of the engine for causing the air admission valveto move independently of the throttle valve into a position to diminishthe air supply to the carburetor and thus increase the fuel supplyproportionately to the amount of air passing the throttle valve when theengine is subjected to an increased load in an intermediate position ofthe throttle valve.

4. A carburetor provided with a main passageway, a throttle valve and anair admission valve, a governing mechanism for the air valve whichmaintains said valve in a certain approximate relationship with thethrottle valve under normal loads, a variable fuel supplying meansoperatively connected with the throttle valve for producing acertainratio of fuel to air in the intermediate positions of the throttlevalve, and a means for increasing the ratio of fuel to air in the eventthe position of the throttle valve is not changed when the load on theengine is increased.

5. A carburetor provided with a main passageway, a throttle valve, ameans governed by the throttle valve for admitting variable amounts ofair to said passageway in the intermediate positions of the throttlevalve and for permitting the air to flow freely through said passagewayin the wide open position of the throttle valve, a fuel supplying devicein said main passageway, a fuel orifice through which fuel is deliveredto said fuel supplying device, calibrated so as to produce the correctratio of fuel to air in the wide open position of the throttle valvewhen the engine is operating under a normal load, means for drawing fuelfrom said orifice into the main passageway by a siphoning action whenthe suction in said passageway drops to minimum, and means forautomatically reducing the discharge of fuel from said orifice when thesuction in the main passageway increases to maximum.

6. A carburetor of the kind described in claim 5, provided with a fuelvalve governed by the throttle valve for restricting the flow of fuelthrough said orifice, more or less, according to the position of thethrottle valve, in the intermediate positions of said throttle valve.

7. A carburetor of the kind described in claim 5, provided with meansfor causing the discharge of fuel from said orifice to varyautomatically in the intermediate positions of the throttle valve, and ameans governed by the suction in the intake beyond the throttle with theair admission valve, a rigid link for I joining the short arm to thethrottle valve arm, an extensible link for joining the long rock arm tothe throttle valve arm, a rigid lever attached to the air admissionvalve and provided with a part that is adapted to coact with said longrock arm to govern the position of said air admission valve according tothe position of said long rock arm when the, engine is in operation,co-acting means on "said long and short rock arms for determining thenormal position of said arms relatively to each other, and a suctiondevice operated by the suction in the intake of the engine beyond thethrottle valve and operatively connected with the lever attached to theair admission valve for moving the long rock arm relatively to the shortroc arm under certain conditions.

9. A carburetor of the kind described in claim 8, provided with a fuelvalve for regulating the supply of fuel to the main passageway undercertain conditions, and a means controlled by the short rock arm forchanging the position of said fuel valve.

10. A carburetor provided With a main passageway, a throttle valve andan air admission valve for said passageway, a mechanism for transmittingmovement from the throttle valve to the air admission valve when saidvalves'are moving towards their closed position, constructed so that theair admission valve is capable of moving independently of and relativelyto the throttle valve, a fuel supply valve governed by the throttlevalve, achoking mechanism for moving the air admission valve into itsclosed position to facilitate starting the engine, and "a deviceoperated by the suction in the intake of the engine beyond the throttlevalve for opening the air admission valve slightly when the enginestarts firing.

- 11. A carburetor of the kind described in claim 10, provided withmeans "for moving the fuelsupply valve slightly away from its seat whensaid choking mechanism is actuated to close'the air admission valve.

12. A carburetor provided with a main passageway, a throttle valve andan air admission valvc for said passageway, a mechanism for"transmittingmovement from the throttle valve to the air admission valve when saidvalves are moving towards their closed positions, constructed so as topermit the air admission valve to move independently of and relativelyto the throttle valve, a ri id arm attached to theshaft of the airadmission valve, a choking mechanism comprising a rock arm whosemovement in one direction causes the air admission valve to close, ayielding bufier interposed between said rock arm and the arm on saidvalve shaft, and a means governed by the suction in the intake of theengine for causing said air admission valve to open slightly when theengine starts firing.

13. A. carburetor provided with a main passageway, a throttle valve insaid passageway, a fuel nozzle-in passageway leading to said nozzle froma source of supply of fuel, an air vent for said fuel passageway, and avalve for said air vent adapted to remain in its closed position whenthe engine is in operation and to o automatically when the engine isstopped:

14. A combined plain tube and mechanical type carburetor for internalcombustion engines, comprising a main air passageway prosaid passageway,a fuel to the throttle valve when the air valve is being used as achokiltig device, during the operation of starting e engine and alsowhen the load on the engine is increased in an intermediate position ofthe throttle valve when the engine is in operation.

WILLIAM G. CARTER.

vided with a suction amphfier, a butterfly valve for said passagewayadapted to be set in a wide open position to cause the carburetor tofunction as a plain tube carburetor or set in a throttling position tocause the carburetor to act as a mechanical carburetor, a fuel supplyingmeans for delivering fuel uninterruptedly to said passageway, means fordiminishing the pro ort1on of fuel to air as the volume of air rou h themain passageway increases when e throttle valve is in its substantiallywide open position, a fuel valveoperatively connected with the throttlevalve the supply of fuel to the main passageway according to theposition of the throttle valve and for maintaining a set ratio betweenthe fuel and the air when the carburetor is functioning as a mechanicalcarburetor, and a manually-operated means for increasing the ratio offuel to air to facilitate starting the engine.

15. A carburetor provided with a main passageway, a throttle valve, anair admission valve, a governing means for the air admission valve whichpermits it to move with the throttle valve, constructed so as tonormally maintain said valves in a certain approximate relationship andpermit the air admission valve to shift relatively to the throttle valveunder certain conditions, a dash pot combined with the air admisslonvalve for retarding the opening movement of said valve when the throttlevalve is opened suddenly to accelerate the e e, a fuel supply devicegoverned by the t ottle valve for regulating the su(pply of fuel to saidmain passageway un er certain operatin conditions, and a suction devicecontroll by the suction produced by the engine for moving the airadmission valve relatively for varying

